1. Technical Field of the Invention
This invention broadly relates to the treatment of sulfur compounds and, more particularly, to the removal thereof from hydrocarbons. The invention still further relates to the removal of sulfur compounds from a fluid hydrocarbon at a time prior to the use of the fluid hydrocarbon as a fuel or as precursor to a subsequent industrial process.
2. Description of the Prior Art and Problems Solved
Sulfur compounds, for example, hydrogen sulfide, mercaptans and sulfur oxides, such as sulfur dioxide and sulfur trioxide, can be produced by natural forces and as by-products of industrial processes. Such compounds, when occurring at certain concentration levels, and, particularly, when released in the gas phase to the atmosphere, are deemed to be at least offensive and, at times, a hazard to the environment. In fact, such compounds are sometimes referred to in the art as "hazardous sulfur compounds" and they are referred to as such herein.
As a consequence of the offensive nature of, and potentially environmental and safety problems posed by, hazardous sulfur compounds their release to the atmosphere has been addressed by governmental entities. Accordingly, hydrogen sulfide and sulfur dioxide are the subjects of 40 C.F.R. .sctn.65, and 40 C.F.R. .sctn.80, respectively.
Certain hazardous sulfur compounds, particularly hydrogen sulfide and mercaptan compounds, are known to occur with fluid hydrocarbons in earthen formations, such as coal beds and subterranean formations which contain oil and/or gas. It is, thus, well known that hazardous sulfur compounds can be dissolved or dispersed in fluid hydrocarbons recovered from such formations and/or separately produced with such hydrocarbons in the gas phase. Regardless of the form of occurrence, and particularly in the case of high concentrations thereof, it has long been important that hazardous sulfur compounds be handled and treated using methods designed to prevent their release, for example, as a gas, to the environment. For purposes of this disclosure, "fluid hydrocarbons" are defined to mean hydrocarbons which occur in the liquid phase, such as crude oil, and hydrocarbons which occur in the gas phase, such as natural gas. Still further, a fluid hydrocarbon containing hydrogen sulfide and/or mercaptans is referred to herein as being "sour." For example, crude oil and natural gas which are recovered from earthen formations and coal beds together with hydrogen sulfide and/or mercaptans have been referred to in the art as "sour" crude and "sour" gas and are referred to as such herein.
In addition to the natural occurrence of hazardous sulfur compounds with crude oil and natural gas, such compounds can also be produced in industrial operations and can result in contamination of refined fluid hydrocarbon products, such as jet fuel, heating oil, petrochemical feedstocks and the like.
Various methods and processes are, and have been, employed to treat hazardous sulfur compounds to prevent their release to the environment. According to some processes, such treatments are conducted at a time when the sulfur compounds are dissolved or dispersed in or otherwise intimately associated with fluid hydrocarbons before the hydrocarbon streams are subjected to refinery operations, used as a fuel or used as a precursor for subsequent operations. Such operations are referred to herein as "upstream" treatments. Other treatments, referred to herein as "down stream" treatments, are conducted after the fluid hydrocarbons have been refined, or used as a fuel or employed as a precursor for the manufacture of hydrocarbon-based products. At such times the fluid streams to be treated are ordinarily waste streams comprised of products of combustion including, hazardous sulfur compounds in the form of sulfur dioxide and sulfur trioxide gas. Flue gas is an example of such waste streams.